Efficacy of a low-dose spinal morphine with bupivacaine for postoperative analgesia in children undergoing hypospadias repair.

BACKGROUND

Children undergoing hypospadias repair need to be protected from highly unpleasant sensory and emotional experiences during and after surgery. We designed a double-blinded, randomized, and placebo-controlled study to compare the efficacy of a low-dose (2 microg x kg(-1)) of intrathecal morphine with placebo for postoperative pain control of children undergoing repair of hypospadias surgery with spinal anesthesia.

METHODS

Fifty-four children were randomly assigned to one of two spinal anesthesia groups. Group M (n = 27) received hyperbaric bupivacaine plus 2 microg x kg(-1) of preservative-free morphine and group P (n = 27) received hyperbaric bupivacaine plus 0.9% NaCl (placebo) under inhalation anesthesia. General anesthetics were discontinued subsequent to the block. The primary outcome was the presence of pain-requiring analgesics during the first 12 h after the spinal block. Side effects were also recorded. The analgesic effects were evaluated by using the Children's Hospital of Eastern Ontario Pain Scale.

RESULTS

Forty-nine patients completed the trial. Fifteen patients (60%) in group P received supplementary analgesics within the first 12 h compared to only four patients (16.7%) in group M (P = 0.005). Mean duration of analgesia was 480 +/- 209 and 720 +/- 190 min in group P and group M respectively (P = 0.009). The groups were similar in postoperative side effects.

CONCLUSION

Spinal anesthesia provided by hyperbaric bupivacaine is adequate for distal hypospadias repair in children, but adding 2 microg x kg(-1) intrathecal morphine provides better postoperative pain control when compared to placebo in these children.